A low pressure system from the Northern Territory was on track to deepen as it collided with a southern cold front, with severe storm warnings for an area stretching from west of Bourke to east of Inverell, and south of Scone expanded to include coastal areas just north of Newcastle on Saturday evening.
On Saturday night those storms reached the coast at Grafton.
They brought damaging winds and large hailstones as well as heavy rainfall.
Twenty millimetres of rain fell in an hour south of Grafton and at Port Macquarie on Saturday night.
Crawney Mountain, south of Tamworth, received 19mm in an hour, while gusts of 105km/h were recorded at Moree airport on Saturday.
There are severe weather warnings in place across the state, with heavy rainfall expected to develop over the Central West Slopes and Plains, the Hunter and the Mid North Coast during Sunday.
NSW has already experienced wet weather for much of the month with floods threatening around the state.
The Bureau of Meteorology's Jane Golding said on Friday the landscape is already "quite sensitive" and floods remain a risk.
"We've seen quite a lot of rain over the last 18 months ... the catchments are saturated, quite a lot of dams are full and some of our rivers are still quite high," she said.
Minor to moderate flooding is predicted on the Belubula and Bell rivers at Orange and Molong, while minor flooding is also set to impact parts of the Upper Macintyre, Gwydir, Peel, Castlereagh and Macquarie rivers.
A moderate to major flood warning is still active for the Lachlan River as its height continues to drop slowly after peaking centimetres below the major flood level on Thursday.
Residents in Forbes in the state's central west were evacuated and farmers in the surrounding areas are counting the cost of lost crops.
Releases from Wyangala Dam are likely to keep river heights up in Forbes but rain forecast for Sunday is not expected to raise levels further.
Ms Golding said the bureau expects the forecast "to evolve quite a bit" as the system develops over the weekend.
"Where the rain falls and the storms develop will depend on which track that (system) takes through NSW," she said.
Meanwhile, two boys were rescued from a flood-affected river in Condobolin on Saturday afternoon.
Emergency services were called after two 11-year-old boys jumped into the Lachlan River, which the bureau has warned could reach a moderate flood level by next weekend.
They were swept 60 metres away by the fast-moving current, made worse by the flood water level, police said.
They were rescued by a police officer who swam out to them with a flotation device.